1. Field of the Invention
The invention relates to a bearing bush with a backing comprising at least one layer, in particular an overlay, on its inner surface, as well as to the use and method for the production thereof.
2. Description of Related Art
Bearing bushes have many uses, e.g. in door hinges, as roller bearing systems, pedal bearings in flexible joints etc.
Depending on the use to which the bushes are to be put and their installation position, said bushes comprise one or two flanges (end flanges) at one or both bush ends. The bushes are installed by interference fit, whereby an immovable fit is ensured. However, this is only achieved if the bush is inserted into an appropriately solid component.
If bushes are to be used in rubber components, the fit is markedly poorer. To remedy this, it has hitherto been attempted to roughen or knurl the outer surface. The resilient material had hitherto to be vulcanised onto the bush, wherein damage could occur to the sliding material of the bush owing in part to the high temperatures occurring during this process. Moreover, where end flanges were to be provided, these had to be flanged later.
For other applications, such as pedal bearings or the like, where the bushes have to be arranged in a pedal lever, additional guide elements, such as bosses, are required, into which two flanged bushes are inserted. This is particularly necessary when the wall thickness of the pedal lever is less than the axial length of the bushes.
A ball bearing system is known from U.S. Pat. No. 3,351,999 which comprises an appropriately shaped bush consisting of a porous metal impregnated with a lubricant. To produce the ball bearing system, a cylindrical bush is inserted together with the ball into a holding device slotted on the outside. By an upsetting process, the bush, and thus also the holding device, is given a round contour, wherein, owing to the external slot, the bush undergoes slight deformation, which is intended to assist fixing in the holding device. In the area of the deformation, the bush does not adjoin the ball, because the deformation does not cause the inner surfaces of the bead-shaped deformation to adjoin each other. The oblique outer surfaces of the deformed areas do not provide the bush with a secure fit.
A plain pedal bearing is known from DE-PS 841 087, in which the bush, in which a tube is mounted, may follow the rocking motion of the tube to a limited degree. To limit the rocking motion, the bush comprises an outwardly directed bead, which may move in a recess provided in an annular component surrounding the bush. The bush consists of steel and does not comprise any sliding coating. The bead is open on the inside and comprises radial slots distributed around its circumference, whereby the stability of the bead is considerably weakened, such that a bush of this type is not suitable for rigid installation with lateral loading, because with time the bush loosens and leaves its original installation position.
U.S. Pat. No. 1,793,874 describes a bearing comprising a curved bush in which a sliding web is inserted. The bush is surrounded by a supporting or holding ring, which comprises one or two bead-type deformations on its outside for fixing in a housing. A sliding web is also arranged between the bush and the holding device, such that the bush is mounted movably in the holding device. This bearing system is complex and expensive owing to the number of components and additionally requires a correspondingly large amount of space.